Sunday, 8 October 2017

Climate Change Effects on Salmon

This summer and early fall are the driest and warmest
we have had, and recent summers have been much the same. Those of us who fish
are justifiably concerned with wild salmon numbers, particularly in rivers
where climate changes will make great difference to salmon.

Sockeye are the most heat sensitive of the five species,
and over 20 Degrees C is lethal to them. If you follow DFO’s sockeye panel
stats, you will know that Qualark Creek temps moved into the lethal range at
times this summer. And note that coho, in saltwater are almost as temperature
sensitive as sockeye.

But there is more to higher temperatures than simply
death. Higher temperature, has been accompanied by lower precipitation in
summer, monsoon rains in the fall, and lower snowpack in winter, setting up
lower flow, of higher temperature, and lower oxygen all summer long.

Lower oxygen is the result of fewer riffles that mix
air and water together. And as chinook are mainstem residers for more than a
year, they suffer the oxygen effects the most. And lower clearer rivers make
fry more visible to predators, thus reducing their numbers.

Pink and chum hatch in March/April and migrate to sea
almost immediately, a period of high flow. The down side for them is that
greater precipitation in winter smothers or washes out egg bearing redds – of
all species really.

But low flow in late summer, can eliminate most water
for pink spawning. They mate in very shallow water, particularly riffles hardly
six inches deep. If those prime spots are only a couple of inches, in addition
to low oxygen, they don’t give the pinks enough depth to spawn, and thus they
move to other water with small pebbles.

Low, warm flow has effects on all species. Chum return
in huge numbers on Van Isle and tend to spawn on greatest flow; this results,
when the water recedes, in huge areas of dead redds. A gravel bar on one river
I fish, is 400 yards wide, and 600 yards long. When the flood subsides, the
entire area looks like it has been bombed with very small munitions. All chum,
and all dead. Chum waste as high a percentage as 90% even in the best conditions.

I started wading through a pool of dead chum, washed
behind a new log – and log movement changes river bed, both scouring out
bottoms and burying bottoms. I calculated 10,000 carcasses and began walking
through. Soon I was up to my thighs, then waist, then chest and rather than go
down with the chum, I slowly backed out of them, and smelled like death all
day.

But there are other effects. If spawning channels have
no water to enter, those fish may not be able to spawn or may move to areas of
lower success, or higher use by other species. If river flow is very low, it
affects chinook the greatest, as they need almost a foot for a 20- to
30-pounder to torpedo through.

I have watched chinook that can hardly move beyond the
tidal reaches of rivers, reluctantly spawn in the highest water, with the
largest gravel. One pair would spawn and go, and the next day, another pair would
dig up the previous redd and also spawn and go. This went on for a full month,
ie. 30 days of repeat spawning and waste of virtually all chinook eggs.

It may be that the sudden rise in merganser numbers about
a decade ago represents another climate change effect. If prey is easier to
see, water is shallower, and slower, fry are easier to catch and eat, so add
predation to climate change effect.

While sockeye have temperature difficulties, and pre-spawn
mortality rises, as shown in Dr. Miller’s work, on Fraser subcomponents to as
high as 90% (also a disease effect, PRV for example), they get an easier pass
by residing in lakes. The downside is that, like Lake Erie that has algal
effects this year on news video, lakes can acidify and become more lethal, in
some cases changing the plankton (a bigger problem in the open ocean) the base
of the food chain.

One effect of lesser obviousness is that lower,
smaller rivers have less spawning space than when at normal levels. That means there
is less main-stem place to spawn, and thus, the respawning phenomenon I have
mentioned, and by more than one species. And the last to spawn would be the fry
of greater numbers, usually chum. However, as chinook are the largest, can move
the largest gravel, chum effect would be greatest on pink salmon and
secondarily chinook, and sockeye.

Coho are a special case. They tend to spawn in side
channels, and seasonal streams. In my winter fishing, I check on several such creeks
to monitor the spawn. As coho can spend an entire summer in seasonal streams,
they are most susceptible to low precipitation – even though coho hold on in
freshwater the longest, in some rivers into January, waiting for highest water.

These days, several streams, don’t get filled up
enough to offer a good spawning chance. Some don’t fill at all anymore and from
being ones where I have watched coho spawn for a decade, have not had water for
the last five, meaning none of those coho survived (unless they spawned in
other water, crowding other coho, too).

And those seasonal creeks usually shrink in low water,
so potholes around root balls, provide the only habitat for coho through one
summer and back into the next high-water event – that means not being able to
migrate out in the first summer.

But in the past few years, I have watched those small
pans of water disappear completely. It is hard to watch water that will support
coho disappear with fry in them. Just so that you know, coho fry have orange
tails, so they are the easiest to identify. As pink and chum migrate out
immediately, chinook are mainstem spawners, and sockeye are associated with lakes,
chances are those fry cutoff from river flow are likely coho.

And when river flow goes down in summer, those small
pools cut off from flow, are likely to kill all fry when/if that happens, it is
coho that are most affected.

There is much more to say, but I will cut to the chase
and end. For several reasons it makes sense for anglers to get involved with
chinook netpens – along with all the other restoration and recovery projects.

Chinook are around 12 months of the year and are our
species of interest. But chinook and coho numbers (particularly in the Salish
Sea for coho since the mid-nineties) have fallen over the years, so that, in
Victoria, we now catch more US chinook in winter, because there are not enough
Canadian chinook.

When you add to this that our orcas are in deep
trouble, and reputed to eat mostly chinook (I’d say this is more because
chinook are around all year, rather than the two months of other species, and
the largest, rather than a dietary preference), it makes great sense to do what
the South Vancouver Island Anglers Coalition has done and put in a netpen in
Sooke Basin to raise and release chinook – for orcas and us.

The argument that that changes things for wild fish
because there is more competition for food resources, I think unlikely, because
there are far fewer wild fish around these days. Other types of competition can
be solved by using diploided chinook that are sterile and thus cannot breed.
Netpen fish also return to the netpen site and can be recaptured by anglers.

When you consider that the CBC – a Toronto-centred
network – has done the Right Whale deaths in the St. Lawrence almost weekly
this past summer, and there are 500 of them, rather than talk loudly about the
78 orcas left, it means we on the BC coast need to be stepping up to fund, or
operate netpens for chinook as much as we can.

I am in contact with a dozen environmental NGOs, and
they repeatedly call for ending the sport fishery to save orcas. I point out
politely that the issue isn’t sport fishing, it is lack of fish, and that the
real key here is to quickly increase chinook numbers. That means a greater
willingness by DFO to authorize netpens, and sport anglers to step up. The
other thing I say is that the people who man such operations are sport
fishermen, and thus that the ENGOs should look upon sporties as allies on
behalf of orcas, rather than enemies. I’d say it will take several years of
polite suggestion for this to sink in.

About Me

I won the national RODERICK HAIG- BROWN AWARD, 2016, for environmental writing, largely for this blog (www.fishfarmnews.blogspot.com) that has become a global portal for the environmental damage made by Norwegian-style fish farms.
I won the Art Downs Award for 2012 for sustained and outstanding writing on environmental issues, in my case, fish farms.
The award was based on 10 columns on fish farm issues in the Times Colonist newspaper, three public submissions to the Cohen Commission on Fraser sockeye and this blog.
If you want to book me to speak, for a lecture, talk, or panel on fish farm environmental damage, contact me on this blog by leaving a message on a post.